1. Field of the Invention
This invention relates to a mount-to-contact type contact on which a terminal of an electric part such as an IC is to be mounted to realize a contact relation therebetween.
2. Brief Description of the Prior Art
In general, a mount-to-contact type contact has a stationary terminal, and a horizontal U-shaped spring portion extending from one end of the stationary terminal, a terminal of an electric part being mounted on a free end of the horizontal U-shaped spring portion to flex the spring portion so that contact pressure can be obtained by reaction thereof.
However, the above-mentioned contact has the shortcomings that since an electric signal flows from the free end of the horizontal U-shaped spring portion to the stationary terminal portion via the horizontal U-shaped spring portion, the path length becomes long, and its characteristics are deteriorated with respect to a high frequency signal.
As one means for obviating the above shortcomings, the present applicant has developed an improved contact which, as shown in Japanese Patent Early Laid-open Publication No. Hei 3-17979 (corresponding to U.S. Pat. No. 5,018,981), has a bypass element disposed at an internal area of the horizontal U-shaped spring portion, one end of the bypass element being in contact with an area in the vicinity of the free end of the horizontal U-shaped spring portion and the other end thereof being in contact with an area of connection between the stationary terminal and the horizontal U-shaped spring portion, a signal being bypassed from the free end of the horizontal U-shaped spring portion to the stationary terminal portion through the bypass element, thus shortening the path length.
Also, in Japanese Utility Model Early Laid-open Publication No. Sho 63-164191, a contact has a shortening projection piece projecting from an upper end of a stationary terminal, and upon downward flexture, a horizontal U-shaped spring portion contacts this projecting piece to form a bypass.
The above contact is effective in shortening the signal path length. However, it has the shortcomings that when the free end of the horizontal U-shaped spring portion is pushed down (in the example wherein the bypass element is provided as mentioned above), a high load is incurred because the spring force of the horizontal U-shaped spring portion and spring force of the bypass element are applied with a multiplier effect, and hazardous contact resistance is increased in view of its characteristics because at least three contact points are formed in the bypass when a signal flows through the bypass element.
In the latter example having the shortening projection piece, downward displacement of the horizontal U-shaped spring portion is restricted by the projection piece, and further push-down force is applied after the horizontal U-shaped spring portion hits the projection piece. Therefore, the terminal of the electric part and the contact are damaged. Moreover, the horizontal U-shaped spring portion is sometimes shifted from a correct position when it is displaced downward and is, therefore, not correctly abutted against the projection piece.